package org.starsource.forum.server.util;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.io.File;

public class Thumbnail {
	public static BufferedImage resize(BufferedImage source, int targetW, int targetH) {
	// targetW，targetH分别表示目标长和宽
		int type = source.getType();
		BufferedImage target = null;
		double sx = (double) targetW / source.getWidth();
		double sy = (double) targetH / source.getHeight();
		//这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放
		//则将下面的if else语句注释即可
		if (sx > sy) {
			sx = sy;
			targetW = (int)(sx * source.getWidth());
		} else {
			sy = sx;
			targetH = (int)(sy * source.getHeight());
		}
		if (type == BufferedImage.TYPE_CUSTOM) { //handmade
			ColorModel cm = source.getColorModel();
			WritableRaster raster = cm.createCompatibleWritableRaster(targetW, targetH);
			boolean alphaPremultiplied = cm.isAlphaPremultiplied();
			target = new BufferedImage(cm, raster, alphaPremultiplied, null);
		} else {
			target = new BufferedImage(targetW, targetH, type);
		}
		Graphics2D g = target.createGraphics();
		//smoother than exlax:
		g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY );
		g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
		g.dispose();
		return target;
	}
	public static void saveImageAsJpg (String fromFileStr,String saveToFileStr,int width,int height)
	throws Exception {
		BufferedImage srcImage;
		// String ex = fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
		String imgType = "JPEG";
		if (fromFileStr.toLowerCase().endsWith(".png")) {
			imgType = "PNG";
		}
		// System.out.println(ex);
		File saveFile=new File(saveToFileStr);
		File fromFile=new File(fromFileStr);
		srcImage = ImageIO.read(fromFile);
		if(width > 0 || height > 0) {
			srcImage = resize(srcImage, width, height);
		}
		ImageIO.write(srcImage, imgType, saveFile);
	}
}